The invention relates to a device for providing position galvano magnetic feedback for electrodynamic drives having a drive coil in an air gap penetrated by the magnetic field.
It is known that in electrodynamic drives the force which is exerted onto a coil in a ring-shaped air gap penetrated by the magnetic field may be utilized to position that coil. Such drives are primarily employed in loud speakers. Additional utilization possibilities exist in signal drives when the moved masses have very small dimensions.
For the control of electrodynamic drives it is of importance that the momentary position of the drive coil can be determined as precisely as possible.
This objective is achieved in the preferred embodiment by use of at least one magneto resistor in the air gap, whose control field is the magnetic field.
A practical circuit requires providing one magneto resistor whose resistance value is advantageously determined by a fixed current source.
An alternate circuit involves using two magneto resistors in a potentiometer connection, whose output voltage is evaluated.
Finally, it is also advantageous to couple the coil and magneto resistor(s) together into a position feedback system so that the movement of the drive can be closely controlled.
By the utilization of at least one magneto resistor, a precisely operating galvano magnetic position revertive communication for electrodynamic drives is facilitated such that no large additional expense is required.